Electronic systems face significant challenges for further size reductions, component density and most importantly power density. Many obstacles need to be overcome to meet up to these challenges. Effective heat dissipation and its management coupled with low resistance and low inductance interconnect, combined with the need to provide a low cost package, are but a few of the many barriers.
A conventional power semiconductor package or module includes one or more power semiconductor dies. A power semiconductor die, such as a power MOSFET, has a bottom surface defining a drain contact or electrode, and a top surface that includes a first metallized region defining a source contact or electrode and a second metallized region defining a gate contact or electrode. In general, each power semiconductor die is electrically and thermally coupled to an external pad.
Power semiconductor packages or modules that contain DC—DC converters exist in the market today. Often, the product is packaged in a micro lead frame (MLF) which does not readily accommodate a large number of discrete passive components. Consequently, the discrete passive components must be located externally—reducing the effectiveness of the package in terms of size reduction. For example, circuits such as the boost circuit and compensation components frequently must reside on the exterior of the product and consume additional board space.
DC—DC converters require a significant number of active and passive components. A conventional DC—DC converter requires power MOSFETs, control integrated circuits (IC's), components for setting the operation of the PWM controller, feedback compensation components, capacitive filter elements, charge pump components, and a power stage filter LC (inductor and capacitor) component. In some cases, a DC—DC converter may be comprised of as many as 30 components. These separately housed components occupy a significant amount of space on a printed circuit board (PCB). These components require careful layout and trace routing to avoid stray inductances that can result in poor performance, or in some cases, device failure.
It is desirable to reduce the board space required by this plurality of components and combine these devices into a high density, singly packaged component that houses the key semiconductor devices and associated components as a building block for a DC—DC converter. It would be desirable not to include the output LC filter due to size and due to the fact that this filter is variable with output voltage. It is desirable that this single package minimize stray inductances, provide a high conductivity interconnection between components, provide a high conductivity low inductance path to external interconnect points, and provide an efficient method of transferring the heat internally generated by the converter to the external environment. It is also desirable that this package be low in cost.